U.S. patent number 6,128,543 [Application Number 09/104,052] was granted by the patent office on 2000-10-03 for method and apparatus for collecting manufacturing equipment downtime data.
Invention is credited to Jim Hitchner.
United States Patent |
6,128,543 |
Hitchner |
October 3, 2000 |
Method and apparatus for collecting manufacturing equipment
downtime data
Abstract
A method and apparatus for collecting manufacturing equipment
downtime data which electrically blocks stopped equipment
(production) from restarting until an acceptable reason (either by
code or direct identification) has been entered and recognized by
an electronic logic system. Locking out the restart capability
until the downtime cause has been entered ensures that the causes
for all downtimes are recorded in a timely fashion. This data is
gathered and recorded to measure and define explanations for lost
equipment running time. Other related data may also be
gathered.
Inventors: |
Hitchner; Jim (San Rafael,
CA) |
Family
ID: |
22298422 |
Appl.
No.: |
09/104,052 |
Filed: |
June 24, 1998 |
Current U.S.
Class: |
700/108; 700/174;
700/79 |
Current CPC
Class: |
G07C
3/005 (20130101); G05B 19/41875 (20130101); Y02P
90/86 (20151101); Y02P 90/02 (20151101); G05B
2219/31411 (20130101); Y02P 90/10 (20151101); Y02P
90/22 (20151101); Y02P 90/80 (20151101) |
Current International
Class: |
G05B
19/418 (20060101); G07C 3/00 (20060101); G06F
017/60 (); G06F 019/00 (); G06G 007/66 () |
Field of
Search: |
;701/114 ;706/912
;700/79,80,174,175,108,111 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Gordon; Paul P.
Assistant Examiner: Calcano; Ivan
Attorney, Agent or Firm: Johnson; Larry D.
Claims
What is claimed as invention is:
1. A method for collecting downtime data for powered manufacturing
equipment, said manufacturing equipment adapted for starting,
stopping, and restarting, said downtime data including
manufacturing equipment shutdowns of both mechanical and
non-mechanical nature, said method comprising the steps of:
connecting an independent electronic logic system to the
manufacturing equipment;
electrically blocking the manufacturing equipment from restarting
after stopping until an acceptable reason has been entered and
recognized by the electronic logic system; and
manually entering an acceptable reason into said electronic logic
system to enable restarting of the stopped manufacturing
equipment.
2. The method for collecting downtime data for manufacturing
equipment of claim 1 wherein said manufacturing equipment includes
a circuit interconnecting a power supply source, a stop switch, a
start switch, a latching relay contact, a safety contact, and a
motor starter coil, in which when conditions have been met to
satisfy the safety contact, momentary pressing of the start switch
completes the circuit to turn on the motor starter coil and start
the equipment, said method further
including the step of recording the entered reason for
evaluation.
3. The method for collecting downtime data for manufacturing
equipment of claim 1 wherein said step of electrically blocking the
manufacturing equipment from restarting after stopping comprises
mechanically blocking with electronic controls.
4. The method for collecting downtime data for manufacturing
equipment of claim 1 further including the step of recording the
duration of the downtime event.
5. A method for gathering and organizing downtime data for powered
manufacturing equipment, said manufacturing equipment adapted for
starting, stopping, and restarting, said downtime data including
manufacturing equipment shutdowns of both a mechanical and
non-mechanical nature, said method comprising the steps of:
connecting an electronic logic system to the manufacturing
equipment;
electrically blocking the manufacturing equipment from restarting
after stopping until an acceptable reason has been entered and
recognized by the electronic logic system;
identifying the cause of said manufacturing equipment shutdown via
human sense perception;
manually entering an acceptable reason into said electronic logic
system to enable restarting of the stopped manufacturing equipment;
and
organizing and sorting said manually entered acceptable reasons
with a spreadsheet on a time and priority basis.
6. A method for gathering downtime data for powered manufacturing
equipment, said manufacturing equipment adapted for starting,
stopping, and restarting, said downtime data including
manufacturing equipment shutdowns of both a mechanical and
non-mechanical nature, said method comprising the steps of:
connecting an independent electronic logic system to the
manufacturing equipment;
programming said electronic logic system to recognize and accept a
plurality of manually entered reasons for said manufacturing
equipment downtime;
electrically blocking the manufacturing equipment from restarting
after stopping until an acceptable reason has been entered and
recognized by the electronic logic system;
identifying the cause of said manufacturing equipment shutdown via
human sense perception; and
manually entering an acceptable reason into said electronic logic
system to enable restarting of the stopped manufacturing
equipment.
7. A method for gathering and organizing downtime data for powered
manufacturing equipment, said manufacturing equipment adapted for
starting, stopping, and restarting, said downtime data including
manufacturing equipment shutdowns of both a mechanical and
non-mechanical nature, said method comprising the steps of:
connecting an independent electronic logic system to the
manufacturing equipment;
programming said electronic logic system to accept a plurality of
manually entered reasons for said manufacturing equipment
downtime;
electrically blocking the manufacturing equipment from restarting
after stopping until an acceptable reason has been entered and
recognized by the electronic logic system;
identifying the cause of said manufacturing equipment shutdown via
human sense perception;
manually entering an acceptable reason into said electronic logic
system to enable restarting of the stopped manufacturing equipment;
and
organizing and sorting said manually entered acceptable reasons
with a spreadsheet on a time and priority basis.
8. An apparatus for collecting mechanical and non-mechanical
manufacturing equipment downtime data, said manufacturing equipment
including a circuit switch, a latching relay contact, a safety
contact, and a motor having a motor starter coil, in which the
conditions have been met to satisfy the safety contact, momentary
pressing of the start switch completes the circuit to turn on the
motor starter coil and start the equipment, said apparatus
comprising:
at least one pair of logic contacts connected in series with the
start switch and connected to the latching relay contact to
selectively block the manufacturing equipment from starting;
and
logic means for operating said at least one pair of logic contacts,
said logic means being programmable for accepting a plurality of
manually entered causes for machinery downtime, said logic means
enabling the manufacturing equipment to restart upon manual entry
of an acceptable reason into said logic means.
9. The apparatus for collecting manufacturing equipment downtime
data of claim 8 wherein said at least one pair of logic contacts is
connected in parallel with the latching relay contact.
10. The apparatus for collecting manufacturing equipment downtime
data of claim 8 further including:
a relay coil connected to said logic contacts to close said logic
contacts when the motor comes on, and open said logic contacts when
the motor turns off.
11. A functional operations meter adapted for use as a comparator
for measuring the benefit and detriment of operational conditions
of manufacturing machinery and processes, said meter
comprising:
data gathering means for collecting both mechanical and
non-mechanical manufacturing equipment downtime data, said
manufacturing equipment including a circuit switch, a latching
relay contact, a safety contact, and a motor having a motor starter
coil, in which the conditions have been met to satisfy the safety
contact, momentary pressing of the start switch completes the
circuit to turn on the motor starter coil and start the equipment,
said data gathering means comprising at least one pair of logic
contacts connected in series with the start switch and connected to
the latching relay contact to selectively block the manufacturing
equipment from starting, and logic means for operating said at
least one pair of logic contacts to enable the manufacturing
equipment to restart upon manual entry of an acceptable reason into
said logic means.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates generally to industrial manufacturing
processes, and more specifically to an improved method and
apparatus for collecting data relative to manufacturing equipment
downtime.
2. Description of the Prior Art
Known industrial manufacturing production processes typically
consist of multiple steps, or stages, to produce a given product.
Many, if not all, of the stages include power usage for the control
of each process step. This power usage can be logged to generate a
record as to when the process step was operational, and when it was
not.
When the manufacturing equipment is not running it is referred to
as "downtime". Downtime can either be planned (e.g., no work,
nighttime, etc.) or unplanned (e.g., mechanical breakdowns, spills,
etc.). In some situations, the cause of the downtime may be logged
by hand by the operator into batch records (where such batch
records are kept).
At other times, the cause for a given downtime may be deciphered
from the downtime pattern, if it is distinctive. Or, the cause of
the downtime may exist only in the minds of the operations people,
and subject to their powers of recall. There is no known on-the-fly
dedicated system that exists for data gathering of downtime
causes.
Although major unplanned downtimes can be dramatic enough to
attract corrective action, cumulative smaller downtime losses can
escape unnoticed. Knowledge of all downtime stoppages, their
causes, duration and summation of this information would encourage
corrective action to be taken (or not taken), so that operating
efficiencies could be maximized. Furthermore, the effectiveness of
corrective measures could be quantified.
SUMMARY OF THE INVENTION
The present invention provides a method and apparatus for
collecting manufacturing equipment downtime data. Stopped
manufacturing equipment is electrically blocked from restarting (or
mechanically blocked with electric controls) until an acceptable
reason has been entered (either by code or direct verbiage
identification) and recognized by an electronic logic system.
Locking out the restart capability until the downtime cause has
been entered ensures that the causes for all downtimes are recorded
in a timely fashion.
Typically, this restart prevention consists of controlling a
process motor or device, but customizing may be necessary depending
on the situation. For instance, an electric eye may be installed
across a conveyor line to detect downtime of product flow, because
product can bunch up (like on a bottle packaging line) and stop
production even though the conveyor motor is still running. This
may also include a new gate device to block movement until a proper
code has been entered. Other mechanical blocks may be utilized,
such as (but not limited to) a clutch plate added to a drive shaft.
However, the concept is the same. Normal manufacturing operations
cannot continue after stoppage until an acceptable code for
downtime has been entered by the operator. This data may then be
gathered and recorded to measure and define explanations for lost
equipment running time. Other related data may also be
gathered.
The present invention is in essence a functional operations meter.
As such, it can be used as a comparator to measure the benefit (or,
conversely, the detriment) of various operational conditions.
Presently, for example, raw material specification ranges, process
parameters and system procedures are largely determined by
empirical means. The present invention can be used to define peak
operational conditions more precisely and more easily than prior
methods. Provisions are included in the invention to accept
external data for comparative use.
For example, raw material specifications are typically set by the
raw material vendor who defines normal production standards. As
best as possible the performance range is evaluated by the
purchasing factory, but rarely are the extremes of range available
for evaluation. This method is often accepted as being economically
"good enough".
With the passage of time, raw material specifications may drift
around (within their range, or drift in an unspecified condition).
This change can damage (or possibly even improve) the end product.
If the impact is dramatic enough for detection, the raw material
specification can be tightened back (or written in for the first
time if it did not previously exist). This can increase the raw
material cost. However, this new, tighter range can be quantifiably
compared to performance for a more precise evaluation as described
in the following two paragraphs. This has traditionally been
determined largely by empirical estimations.
The present invention includes provisions for adding reject counts
and unit costs to determine reject material cost. This is usually
known with reasonable accuracy before raw material specs are
changed. Total loss/unit made is equal to reject material
costs/unit made added to downtime labor costs/unit made. Since
downtime losses are known with greater precision with the method of
this invention, a more precise total loss can be determined (or
more easily determined). A curve can be generated by plotting total
losses/unit made against raw material specification values. The
integral under the curve over any range represents the losses per
units made over the selected range.
The tighter the raw material specification range, the more
(generally) the raw material will cost. To ascertain whether to pay
a higher price for a tighter range for a raw material the invention
will support the following format: The loss per unit made from each
lot that used the raw material within the selected narrow range are
added together. This total is divided by the number of lots used
for data to determine the average loss per unit made while staying
within the tighter specification. This process is repeated to
determine the (higher) average loss per unit made while operating
within the wider window raw material specification. Finally, the
ratio of the higher raw material cost per unit made divided by the
normal (broad-band) raw material cost per unit made is multiplied
times the average loss per unit made at the tighter specification
range (to account for the price differential). The lower average
cost is the most profitable choice.
In addition to raw material issues, system changes can impact on
productivity. Presently, many system changes are made intuitively.
A simplistic example would be to move a toolbox closer to the
operator or mechanic. It is often difficult to measure the impact
of a small system change like this amidst the amalgamation of the
"big picture" of a full production line.
The present invention allows the purported improvement to be
quantified by measuring before and after performance. Since the
invention is
downtime-specific, appropriate downtime data can be segregated to
magnify performance. In the toolbox example only repair downtimes
likely to be affected would be displayed (by total/unit time and
average time/incident) using before and after data.
Sometimes these intuitive "improvements" are subtly
counter-productive. Because the present invention can define
downtime so specifically, other local increases of lost
productivity can be identified and reviewed for any possible
association with the initial system change. In the toolbox example,
the closer location could be blocking the flow of material
downstream, which would show up as increased downtime at the
downstream station.
Process changes can also be measured for impact. As an example, if
line speed were increased, the curve of actual total costs per unit
made would first show the downward slope of reduced production
costs per unit made (due to the faster line speed); followed by a
reversal of slope direction upward of increased production losses
per unit made (due to inefficiencies of the higher speed). Peak
productivity occurs where the slope is minimal (D.sub.y /D.sub.x
=0). Presently this is determined mostly by empirical means. This
invention refines the precision, and/or makes the determination
easier to define.
Novel features of the inventive method and apparatus include, but
are not limited to, the following:
A. Forced manual prompt for downtime cause. The method of data
entry is unique.
B. Downtime reports (with causes) for normal industrial production,
as opposed to mere productivity reports.
Everyone is aware of downtime; it's that which reduces
productivity. If downtime did not exist, nothing would ever go
wrong and total output would equal theoretical production rate
times time worked. Downtime is the "friction" that prevents
production from being perfect. Intuitively, if one measures
productivity, it would seem that there is no apparent reason to
measure downtime, because it is simply that amount which is missing
from productivity. However, tracking downtime allows its causes and
categories to be tagged with it. Displaying downtimes by various
assorted flags is diagnostically useful for reducing and
eliminating an appropriate portion of it. Itemized downtime reports
can be used to diagnostically reduce downtime.
C. Unlike other existing systems dedicated to specific uses, the
diagnostic solutions are not spoon-fed to a machine over wires.
This invention has a more generic concept to make an affordable
production management system available to most all industries.
Management people (human beings) have to look at the data produced
by this invention for trends, totals, causes, etc. Then they must
decide what corrective actions they want to take. This is the way
that business has always been run. Industry gathers the best data
they can afford and makes the best decision they can. This
invention gives businesses better data at an affordable price. (The
cost is affordable because of its design and pre-packaged software
core.) As may be readily appreciated, the present invention
provides data regarding mechanical and non-mechanical causes of
downtime. For example, in a downtime data environment, data that
underlies and generates management decisions regarding employee
participation in the production process is considered to be of a
non-mechanical nature. Non-mechanical downtime data includes
categories such as staff training needs and placement, human error,
and planned downtimes (for such things change over and set up), as
is set forth below in paragraphs E, F, and I.
D. Further separation of downtime data into subdivisions of planned
and unplanned downtime events. Pre-splitting downtime into planned
and unplanned categories enables evaluation of preventive and
non-preventive measures.
E. Allocation of downtime data sorted by employee numbers to detect
a need for additional training and/or for best staff placement of
employees (an algorithm may be written to do this
automatically).
F. Downtime causes created by human blunders escape other systems.
Because they do not lend themselves to electrical sensor input,
automation cannot cope with this non-electrical event, yet during
many production operations human problems may account for more than
half of the outages. Of even greater significance, these represent
perhaps the most preventable of the downtime events.
G. The key downtime data (cause) is fed immediately to the computer
as it happens.
H. The quality of productivity data will be more accurate, because
existing productivity reports can mask downtime amounts and causes.
Downtime reports display all the "bad news". But, only if one knows
what the "bad news" is can anything be done to prevent it. Many
production rates can be "pumped up" for short bursts to mask a
downtime event. Then management does not know that a faster rate
may be possible, and they do not know that something went wrong
that might need to be changed so it does not happen again. This
does require management to be more enlightened and less vindictive,
because the workers can often offer corrective ideas to solve
problems.
I. Planned downtimes of similar character can be measured against a
standard (equivalent downtimes should be of comparable duration).
Production run times are often known, but change over (set-up)
times are accepted as is for whatever turns out. Often, substantial
equipment time can be lost during set-up time which could have been
spent productively. In most cases, this set-up time is not
comparatively monitored because real set-up times are based not on
the new set-up alone, but the difference between the new and the
previous setting. This invention has the capability of
distinguishing the various categories of set-ups and establishing
separate standards for the nuances of each. In addition, standards
for any repetitive planned downtime can be established to monitor
this out-of-control lost time.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 (Prior Art) is a schematic view of a typical manufacturing
production control logic circuit consisting of hardware and/or
software components;
FIG. 2 is a schematic view of a motor control logic circuit of this
invention, illustrating two modifications that may be made to the
existing equipment illustrated in FIG. 1; and
FIG. 3 is a schematic view of the conceptual logic of this
invention external to existing equipment.
DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT
Definitions:
Downtime: Any time manufacturing operations are not producing
product.
Electronic Logic System (ELS): A PC and/or a PLC.
Manufacturing Production Equipment: Any electrical device, or
plurality of devices, that modify a material in such a way as to
make, or contribute toward making, a final product more marketable.
(Used implicitly throughout this specification as being equivalent
to manufacturing operations.)
Momentary Closed: Electrical contacts that remain electrically
"off" until a pushbutton is pressed by an operator. As long as the
button is pressed in, the contacts are closed (electrically "on").
When the button is released the circuit reopens. In software logic
this functions as a close pulse.
Momentary Open: Reverse of Momentary Closed. Electrical contacts
that remain closed (electrically "on") until a pushbutton is
pressed by an operator. Then the contacts open (electrically "off")
and remain open only as long as the button is held in. When the
button is released the contacts reclose. In software logic this
functions as an open (circuit-breaking) pulse.
Motor Control Starter Coil: The relay coil, whether actual hardware
or embedded in software, that starts the device.
Motor Starter: Same as motor control starter coil.
PC: Personal computer, the common computer.
Planned Downtime: Anticipated downtime, such as at night, cleaning,
lack of need, set-up time for a different product, preventive
maintenance, etc.
PLC: Programmable logic controller, an electronic package that
contains some or all of the following features: internal relays,
timers, counters, logic, etc.; and external output relay contacts,
analog control signal outputs, input terminal contacts, keyboard
input interfaces, etc.
The Device: Same as manufacturing production equipment; the entity
being monitored for downtime.
Unplanned Downtime: Unexpected downtime, such as occurs due to
equipment breakage, lack of feed material, etc.
Referring now to FIG. 1, a typical manufacturing production control
logic circuit may include the following hardware and/or software
components:
Power supply source 10. This may be 120 volts, 24 volts, 12 volts,
5 volts, etc., using either alternating (AC) or direct (DC)
current, as long as the voltage is compatible with the
components.
Circuit completing common (or neutral) return leg 12 to complete
the circuit back to the source.
Stop pushbutton (switch) 14. It can be either a single switch, or
more than one, as shown. It is installed in series with the main
logic circuit. It has been historically installed as momentary open
hardware, but can also be built into software as safety allows. For
example, it may consist of a momentary (press & release),
normally closed style pushbutton used by the operator to stop the
motor (or other device).
Start pushbutton (switch) 16. It can be either a single switch, or
more than one, as shown. It is installed in parallel with the motor
latching relay contacts 18 in the main logic circuit. It has been
historically installed as momentary close hardware, but can also be
built into software as safety allows. For example, it may consist
of a momentary (press & release) normally open style pushbutton
used by the operator to start the motor (or device).
Latching Relay Contacts 18. This is a normally open style auxiliary
contact physically located adjacent to the motor starter coil
(described infra). When the start button 16 is pressed, the motor
starter coil is activated (as long as all the safeties are
satisfied), the latching relay contacts 18 close and, because of
these contacts 18, the motor keeps running after the start
pushbutton 16 is released.
Safety Contacts 20. They can be normally open style (as shown) or
normally closed, as logic warrants. They can be relay contacts,
pressure switches, alarm contacts, etc. They are wired in series
with the motor starter coil as shown but are typically installed in
front of the stop button to minimize the length of hot wires. They
are functionally correct but are shown here after the stop button
14 for schematic clarity. These can vary from none to an
unrestricted count in number depending on the application. They can
be either in hardware or embedded in software. They are typically
used to assure that the safety and process parameters are, and
remain, met.
Thermal overload protector such as a fuse 22 (shown) or circuit
breaker.
Other Safety (or Operational) Devices 24: These include proximity
switches (for guard-in-place, etc.), trip wires (to keep hands and
bodies away, etc.) and other miscellaneous devices to shut the
equipment off, which are not otherwise covered under safety
contacts 20. Their physical location is as described for the safety
contacts, supra.
Motor Starter Coil 26: This is a relay coil typically sold in a
package to start a motor. It has three contacts for operating a
three phase electrical motor. It is connected to a fourth pair of
contacts 18 to latch the circuit closed for running. It
occasionally has additional auxiliary contacts for logic use, in
which case an extra coil (described infra) is not needed. The
device has been called a motor for convenience throughout this
schematic; but it can be any electrical device, such as a heater,
solenoid, etc.
When the conditions have been met to satisfy all of the
process/safety interlocks 20, 22, 24, momentary pressing of the
start button 16 completes the circuit from power supply source 10
to common return leg 12 to turn on the motor control starter coil
26. The motor control starter coil 26 has multiple contacts, some
of which start the device. The pair of normally open contacts 18 in
parallel with the start button 16 are closed by the motor starter
26 to latch in (i.e., lock to the on position) when the start
button 16 is released. These latching contacts 18 are what keeps
the device running after the start button has been released.
A momentary (or longer) break in the circuit from power supply
source 10 to common return leg 12 by pressing the stop button 14 or
by opening any of the safety/process contacts (interlocks) 20, 22,
24 causes the motor control starter coil 26 to de-energize. When
motor starter 26 de-energizes, the latching contacts 18 fall out
(open). After the cause for the stoppage has been rectified, and
all the permissive contacts (at stop button 14, safety contacts 20,
fuse 22 and other safety devices 24) have been satisfied again, the
device will not restart because the latching contacts 18 (which
dropped out when the device was shut off) will remain open until
the start button 16 is pressed again. This sequence is repeated as
necessary to start and stop the device.
FIG. 2 is a schematic view of a motor control logic circuit of this
invention, illustrating two modifications that may be made to the
existing equipment of FIG. 1. The present invention introduces an
additional pair of contacts as logic contacts 30 in series with the
start button 16 and in parallel with the latching contacts 18. This
contact arrangement is unusual since it only blocks the device from
starting. It does not (unlike the safety/process interlocks) stop
the device once it is running. Process/safety interlocks must stop
the device in the fail mode, both from running as well as to
prevent the device from starting, and are installed in series with
the main logic circuit leg as described supra. These logic contacts
30 function as and will usually be normally open style, but could
be physically normally closed style if logic conditions require it.
Contacts 30 could be physically placed anywhere in the circuit, but
logic will force the contacts 30 to behave as if placed where
shown. They will never stop running equipment from running; they
will only prevent stopped equipment from restarting.
Optionally, secondary relay coil 32 is a supplement to the motor
start coil 26. The motor start coil 26 rarely has spare contacts.
This new relay coil 32 merely expands the motor starter's contact
capacity by two or more additional pairs of contacts. It is active
when the motor is on. It closes the new logic contacts 30 and opens
the motor status contacts 50 (described and illustrated in
conjunction with FIG. 3, infra) when the motor comes on. It
reverses the action when the motor drops out.
A possible concern of management is that, during retrofit
installation of the inventive apparatus, any kind of tinkering
might shut the production down. The fact that there are only two
modifications, and both are simple, minimizes the risk of problems
to existing equipment. Furthermore manual bypass contacts (not
shown) can be temporarily installed to bypass the contacts 30 and
keep all stations running until the system has been debugged.
The logic contacts 30 are controlled by a separate circuit. FIG. 3
is a schematic view of the conceptual logic external to the
existing equipment, and includes the following components:
Decision Device 40: This may be either a PC (personal computer) or
a PLC (programmable logic controller), depending on the situational
needs.
Permissive coil 42: This coil closes the new logic contacts 30
installed in the existing equipment to allow the motor to start.
Permissive coil 42 can also be used to close the status indicator
contacts 46, infra.
Decision Device Contacts 44: When the decision device 40 is
satisfied with the downtime cause input via keypad 52, it closes
decision device contacts 44 to activate (start) the permissive coil
42. As soon as the motor stops, motor status contacts 50 advise the
decision device 40 that the motor is down, and the decision device
40 opens these contacts 44.
Status Indicator Contacts 46: These contacts activate the status
circuit.
They are typically normally open style contacts as shown. They are
controlled by the decision device 40 (for logic) and the permissive
coil 42 (for hardware).
Status Condition 48: This can be as simple as an indicator light
(as shown), and/or as sophisticated as a displayed message on a
monitor or computer screen. It advises the operator that the
inventive circuit has been satisfied, and the equipment is ready to
go if everything else has been satisfied. It can be activated
either by the status indicator contacts 46, or else directly from
the decision device 40 itself.
Motor Status Contacts 50. These contacts are physically closed when
the motor is running, and open when the motor stops. They can be
normally closed style (as shown) or normally open style as long as
the action is consistent with the logic.
Keypad 52: This MMI (man to machine interface) allows the operator
to provide the required data.
Data is input by an operator via keypad 52 (or any other
appropriate input means, such as touch-screen keypad, voice
recognition, etc.). The data represents a codified or real
description for the cause of an existing downtime. The input data
is screened by electronic logic system 40 for acceptability. If
rejected, the input data entered at the keypad may be cleared and
new data entered. If the downtime event is of long duration logic
allows multiple causes to be assigned proportionately to the
downtime interval.
If the electronic logic system 40 passes the input data, it
activates permissive relay coil 42 via a momentary pulse closure of
normally open decision device contacts 44 in series with the
permissive coil 42 (connected as necessary to hardware). Permissive
coil 42 may include a pair of contacts 30 (FIG. 2) that close so
the device start button 16 can operate when pressed, and a third
pair of normally open contacts 46 that close to energize permissive
indicator 48 (by light or displayed message).
The logic coil circuit can be completely software-based,
hardware-based, or a mixture of hardware and software. Other
related data can be entered as appropriate, e.g., at the start of
the day, at the start of the batch, as employees change, or as
keyed to process changes.
In its simplest format one digit (of 10) can be used at the
keyboard 52 input to the electronic logic system 40 to indicate
input cause of downtime data.
The inventive system thus provides a flip/flop circuit that
mandates that a downtime entry be given in order to restart the
device. Restarting the device clears out the downtime entry from
being reused. Stopping the device requires another downtime entry
in order to restart the device.
All the downtime duration data and causes, along with related data,
may be gathered and sorted as per filter screens of a spreadsheet.
Then this data may be tabulated and displayed in an appropriate
database or spreadsheet, such as EXCEL 97, SQL or ACCESS.
Typical of an information system, there are three basic
subdivisions. There is an input package, a transmission package and
an output package. Since these packages may be utilized by various
clients in various industries, no two systems will be identical.
However, within each subdivision there are similarities. Existing
equipment will generally be modified to include one extra set of
permissive contacts to start each piece of equipment. The contacts
will latch and stay latched until the equipment stops running by
any means previously used to stop it, and then the latching logic
will drop out. Other modifications may be necessary to gather
additional data requested by the client (such as rates of
operation, station step, etc.). However, they may follow a
generalized program as described next, but custom-tailored to each
need.
Modifications to Existing Equipment to Receive Input Data Start
Boxes
Each "Monitored Piece of Equipment", also known as a "Unit
Operation", will be referred to as a "Station" for the balance of
this system description. Each station will receive a minimum
modification, consisting of insertion of an additional pair of
permissive contacts and feedback from the station starter
confirming start-up. Furthermore, a new "Start Box" is connected to
the "Input Data Gathering Base", both of which are totally
independent of the client's existing system. There are two basic
ways (personal computer or programmable logic controller) to
provide a start station package. When PC's (Personal Computers) are
used at a station, the Start Box and Input Data Gathering Box are
likely to be together and dedicated.
PC inputs offer more choices because of their greater computing
power. Typically there would be a normal computer screen and
keypad. However, PC's can be modified to have a touch screen.
Touching an area of the screen that looks like a button or other
mnemonic image can often allow faster data flow. Voice recognition
is an even more elegant choice when a hands-free input is
needed.
PLC's (programmable logic controllers) can be used in place of
PC's, and they are generally more rugged. PLC's are commercially
available devices from Allen Bradley, Siemens Inc., and numerous
other sources that consist of terminals for input and output data,
both digital and analog; where the input data can be logically
evaluated and processed against time, count and other data. Another
way to look at it is to consider it to be a box of relays, timers,
counters and constants that can be wired using a PC (once it has
been wired the PC is no longer needed).
The PLC's are expected to be remote from their Start Boxes and
would generally be expected to process data from multiple Start
Boxes. The Start Box for PLC driven stations will typically consist
of a keypad and brief display screen.
A client may request that production rates or other information be
tagged to the downtime data. This will likely require other
modifications to the existing equipment to intercept this
information most conveniently for the operator. Other custom
modifications may be required to meet individual customer
requirements as they arise.
There are as many Start Boxes as there are (monitored) Stations in
a factory.
Input System Package
Built into each station will typically be its identity. It will
reside in its Input Data Gathering Base (IDGB). All data gathered
from each of these stations will be tagged with the station
identification. All downtime data will be later dividable into the
tagged categories for sorting by tagged categories. Station
identification will be built-in and will require no operator
input.
When an operator first attempts to start the station via the new
Start Box in a typical operation, he will be prompted to enter his
employee number. The IDGB will verify each entry as eligible.
Additional employee entries are permissible up to a limit
established by the client for maximum employees/station for each
station.
The next prompt is for a product code. The IDGB will check to
verify if entry is eligible. If it is different from the previous
entry, a downtime entry for cleaning may be confirmed as a
permissive if desired by the client. A basic multi-client program
may include many provisions like this, citing these optional
features for inclusion or deletion. Deletion of these pre-written
features can occur more easily at the time of client installation
than adding custom code to a core program. Only one entry for a
product code is allowed at a time.
The next prompt is for lot number. After checking for acceptance
the standard program will query for an "Are you sure?" response
from the operator if the lot number is not running sequentially
with the previous numbers.
The last prompt is for the cause of the existing downtime, which at
the beginning of the day is typically the code for:
"Planned/Overnight." Pressing the Start Button now will start the
equipment.
The IDGB permissive contacts will remain latched and the station
will remain running as multiple employees come and go (as long as
at least one remains logged on), and lot numbers may change without
shutting down (if this is consistent with client-company
policy).
However, once the station stops for any reason that it would have
stopped for in the past, the latched contacts drop out. The IDGB
detaches the run-enable mode and starts logging (off) downtime. The
operator must enter a cause for the stoppage before the equipment
can restart. The IDGB will verify the legitimacy of the entry and
latch for restart. Depending on how the Start Box is configured,
allowance can be made for custom messages to be typed in downtime.
Multiple entries for entries for downtime causes are allowed,
including entries identifying mechanical or non-mechanical downtime
causes, or both, but the mandate is: at least one must be entered
in order to continue.
Corrections to downtime causes may be typed in and transmitted to
the IDGB prior to restarting. Once restarted the original data is
erasable, but displayed in a modified font.
As soon as the new feedback coil acknowledges that the station is
running again, the IDGB calculates the time interval that the
station was down (alternatively, the differential time interval can
be calculated on the spreadsheet or database processor). It also
subdivides this interval by any other changes (staffing, etc.) that
occurred during the downtime interval. All of this data is keyed to
the start of the downtime and stored in the IDGB for transmission
to a central data base.
An exception for restart blockages will be allowed in the set-up
and related modes so as not to impede the set-up process.
Appropriate limitations will prevent abuse of this bypass.
There are multiple Input Data Gathering Bases, albeit not
necessarily as many as the Start Boxes, since multiple Start Boxes
can be ganged onto single IDGB's.
Transmission Package
Depending on the capacity and format of the data highway used by
the client, one can either install a new independent Local Area
Network (LAN) or use the existing LAN system, or connect the input
with the output database/spread sheet processor directly if the
system is small enough. A description of some typical transmission
systems follows:
A burst-mode transmission system functions as follows: Triggered by
real clock time, midnight for example, all of the data that has
been accumulated in the IDGB will be transferred to a storage disk
for permanent filing and a duplicate will be sent to the Master
Output Spreadsheet/Database Processor(s).
A dynamic transmission system functions on-the-fly as follows:
Conversely, the trigger may merely be a change of state at the IDGB
if the output is used as the workhorse for data manipulation and/or
the IDGB's memory is limited.
Depending on final client system capacity, the LAN may split the
output load into segments for output processing by more than one
Output Spreadsheet/Database Processor (OSDP). The LAN will confirm
the validity of the transmission, then stagger-erase (cascade
disappearing data by holding it until verification of valid receipt
before erasing the oldest data). After the LAN is satisfied it will
command the local IDGB's to clear and reset their input logs. It
will also command the OSDP(s) to start processing. The LAN will
make one last confirmation of the IDGB instructions to confirm
proper erasure and performance, and then it will go back to sleep.
In other words, each time data is transmitted, it will be checked
for valid transmission before erasing, and the data at the output
will be recorded on tape or equivalent for a permanent record.
Besides the normal wake-up call of the LAN, it will be awakened by
any detectable Priority 10 (highest) Failure of an IDGB for
immediate network alarm transmission. It will also transmit
category information (new employee names, new downtime causes, new
lot numbers, etc.) from the OSDP's to the IDGB's as needed.
There is normally only one LAN required.
Output Spreadsheet/Database Processor
The Output Spreadsheet/Database Processor (OSDP) is a commercially
available spreadsheet preprogrammed with macros and other software
as needed to receive the transmitted input data, sort and organize
it into a master format, and print these reports on a prescheduled
time frame. Additionally, the structure can be organized so that
sorting of downtime data can be presented in any tag priority
sorting, on any time basis (capacity allowing).
It is preferable to leave the tag variables, and especially the
Downtime Cause Tags, to be as accessible and free for client
modification as possible.
Modem ports (controlled by the client) may allow remote
troubleshooting of future problems that may occur to help the
client reduce their maintenance costs of this system.
Benefits of the inventive method and system include:
1. Prior art downtime reports, such as they exist, do not segregate
planned downtime from unplanned downtime. The present invention
separates planned and unplanned downtime (based on the cause).
2. Presently, the causes for downtime come from operator
recollections and/or scouring over cryptic batch notations such as
they exist. This is after-the-fact data. The present invention
couples entry of a downtime cause with blockage of restarting the
device, and forces collection of timely (more accurate) data.
3. Collection of on/off data via an ammeter recorder or voltmeter
recorder do not identify causes of downtime because they would be
limited to only identifying causes that could be pre-programmed
into them. This precludes all human-type errors and would limit the
number of identifiable machine-caused downtimes to a uselessly
small number in most cases.
4. Data entry can be as fast as a one key entry (for 0 through 8
general causes, 9 preferably being reserved for other data) for
minimal delay of production resumption. Speed of data entry is
important in that slow complicated data entries reduce the
reliability of the data and extend the downtime by delaying restart
of the device.
5. The data entry format, although geared for speed, can be quickly
modified in the field at the electronic logic system for more
detailed (e.g., expanded digit or narrative text) entries for
trouble shooting when warranted.
6. Planned downtime, as well as the obvious unplanned downtime, can
also be broken into categories in order to measure cleaning and
set-up times.
While this invention has been described in connection with
preferred embodiments thereof, it is obvious that modifications and
changes therein may be made by those skilled in the art to which it
pertains without departing from the spirit and scope of the
invention. Accordingly, the scope of this invention is to be
limited only by the appended claims and equivalents.
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